title: A psychometric cut-point to separate emergently suicidal depressed patients from stable depressed outpatients.
abstract: BACKGROUND
  The design of safe clinical trials targeting suicidal ideation requires operational definitions of what degree of suicidal ideation is too excessive to allow safe participation.
  
  
  OBJECTIVE
  We examined the Scale for Suicide Ideation (SSI) to develop a psychometric cut-point that would identify patients having a suicidal emergency.
  
  
  METHODS
  The Emergency Department (ED) and the out-patient clinic of a university hospital.
  
  
  METHODS
  We used the SSI to contrast 23 stable, depressed adult out-patients versus 11 depressed adult ED patients awaiting psychiatric admission for a suicidal emergency.
  
  
  METHODS
  The performance of the SSI was examined with nominal logistic regression.
  
  
  RESULTS
  ED patients were older than out-patients (P<0.001), with proportionally more men (P<0.05), and were more ethnically diverse than the outpatients (P<0.005). Compared to out-patients, ED patients were more depressed (Patient Health Questionnaire-9 score 23.1±3.8 vs. 11.7±7.3, P<0.005) and reported a greater degree of suicidal ideation (SSI scores 25.7±7.3 vs. 4.2±8.4, P<0.0001). Nominal logistic regression for the univariate model of SSI score and group yielded a score of 16 (P<0.0001) as the best cut-point in separating groups, with a corresponding Receiver Operating Characteristic Area Under the Curve = 0.94. Of 34 patients in the total sample, only two were misclassified by SSI score = 16, with both of these being false positive for ED status. Thus, the sensitivity of the cut-point was 100% with specificity of 91%. When the model was expanded to include SSI along with age, gender, ethnicity, sedative-hypnotic use, and over-the-counter use, only SSI score remained significant as a predictor.
  
  
  CONCLUSIONS
  A SSI score ≥16 may be useful as an exclusion criterion for out-patients in depression clinical trials.
authors.affiliation: Department of Psychiatry and Behavioral Medicine, Wake Forest University School of Medicine, Winston Salem, NC, USA ; Department of Psychiatry and Health Behavior, The Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA.
authors.forename: W Vaughn
authors.initials: WV
authors.lastname: McCall
authors.forename: Nicolas
authors.initials: N
authors.lastname: Batson
authors.forename: Megan
authors.initials: M
authors.lastname: Webster
authors.forename: Indu
authors.initials: I
authors.lastname: Joshi
authors.forename: Todd
authors.initials: T
authors.lastname: Derreberry
authors.forename: Adam
authors.initials: A
authors.lastname: McDonough
authors.forename: Suzan
authors.initials: S
authors.lastname: Farris
keywords: Depression; emergency department; suicidal ideation